Question

If earth be a homogenous sphere and has hole in it from one side to another if a iron ball is dropped in it where will the ball go

Answer 1

It will simply oscillate from one end to the other end but then there are 2 conditions like if there is a vaccum in that empty part it will oscillate forever if not if it has atmosphere in it will just slow down and down and down eventually getting at rest in the middle part of the sphere as it is homogeneous.